Polysilicon fuses are used in semiconductor devices or packages due to their advantages including the ability to be blown without an opening to allow fused by-products to escape as required with metal fuses. Polysilicon fuses can thus be used for trimming during wafer sort, final test, and in customer applications.
Typically polysilicon fuses have a layer of silicide over the fuse to form a low resistance conductor for the current densities required to generate the heat to create a discontinuity in the polysilicon and in the silicide. However, the fuse must be designed, and the proper fuse current must be used to prevent the silicide flows from reforming the electrical connection across the fuse after it has been initially blown.